Amount Of Total Lipids Research Articles

Nutritional status response of daphnia laevis and Moina micrura from a tropical reservoir to different algal diets: Scenedesmus quadricauda and Ankistrodesmus gracilis.

The accumulation of lipid reserves was investigated in two common cladoceran species typical of neotropical freshwaters. Experiments were performed in order to measure differential accumulation of lipid reserves in response to two algal diets, S. quadricauda and A. gracilis. The larger D. laevis fed with the Ankistrodesmus diet accumulated a higher amount of total lipids. The average lipid content for both diets was 1.1% and 22.1% dry weight for Scenedesmus and Ankistrodemsus, respectively. This difference was found to be highly significant. The superior nutritional quality of A. gracilis was confirmed by the experiments using the smaller Moina micrura. This cladoceran accumulated 11.4% and 19.9% of the average dry weight of lipids from Scenedesmus and Ankistrodesmus, respectively. The study also found that most lipid reserves are concentrated as triacylglycerols in both cladocerans. The relative contribution of this class of lipids also varied according to the diet. For Daphnia, for instance, the average triacylglycerol levels varied from 6.2 to 11.0 with the Scenedesmus and Ankistrodesnus diets, respectively.

Organic matter in a subtropical mangrove-estuary subjected to wastewater discharge: Origin and utilisation by two macrozoobenthic species

Total lipid amounts, fatty acid signature analysis, and C:N measurements were used to investigate the sources of organic matter in an Okinawan estuary (Okukubi, Japan) during the 1999 rainy season. This estuary has a mangrove forest and receives agricultural wastewater. Highest concentrations of total lipids and lowest C:N values were simultaneously found near the pipe where the agricultural water is discharged. Fatty acid profiles in the sediments varied among the stations, indicating differences in the contributing organic sources. Small amounts of lipids and low relative contributions of long-chain fatty acids, markers of vascular plants, were found at stations within and adjacent to the mangrove. These results indicate that the export of organic matter from the mangrove litter to the intertidal flat was limited and spatially restricted. The wastewater seems to induce high amounts of bacteria, macroalgae and benthic diatoms, as indicated by their respective fatty acid markers. The fatty acid profiles of the tissues of two dominant intertidal invertebrates, the crab Uca vocans and the gastropod Terebralia sulcata, indicated that their diet was largely comprised of bacteria. Green macroalgae were important food sources for the gastropods; diatoms and mangrove biomass contributed to the nutrition of the crabs, although their contributions were smaller.

The metabolic basis of life history variation: genetic and phenotypic differences in lipid reserves among life history morphs of the wing-polymorphic cricket, Gryllus firmus

The flight-capable morph of the wing-polymorphic cricket, Gryllus firmus, accumulated a substantially greater quantity of total lipid and triglyceride, compared with the obligately flightless morph, during the first five days of adulthood. Increased lipid accumulation in the flight-capable morph was genetically based, and was produced when ovarian growth is substantially reduced in that morph. Temporal changes in lipid levels suggest that the higher triglyceride reserves in the flight-capable morph fed a high-nutrient diet were produced by elevated lipid biosynthesis. By contrast, on a low-nutrient or high carbohydrate diet, increased lipid levels in the flight-capable morph appeared to result primarily from decreased lipid utilization. Increased biosynthesis or retention of triglyceride (the major flight fuel in Gryllus) by the flight-capable morph may significantly divert nutrients from egg production and hence may be an important physiological cause of its reduced ovarian growth. The obligately flightless morph allocated a greater proportion of total lipid to phospholipid than did the flight-capable morph. No functionally-significant differences in total lipid or triglyceride were produced between morphs during the last nymphal stadium. A second flightless morph, derived from the flight-capable morph by histolysis of flight muscles during adulthood, also had reduced amounts of total lipid and triglyceride but increased ovarian growth compared with the flight capable morph on the standard (high-nutrient) diet. Important qualitative and quantitative aspects of lipid metabolism differ genetically between the flight-capable and flightless morphs of G. firmus and likely contribute importantly to their respective adaptations for flight capability vs. reproduction. This is the first study to document genetically-based differences in energy reserves between morphs of a complex (phase, caste, flight) polymorphism in which morphs also differ genetically in key life history traits.

ω3‐Fatty Acids in Some Fish Species from Turkey

ABSTRACT: The polyunsaturated ω3‐fatty acids, eicosapentaenoic acid and docosahexaenoic acid, have positive effects against to cardiovascular diseases. This work was carried out to investigate the fatty acid composition of the most popular fish from Turkey (mainly Istanbul area) and their nutritive values. Total lipid amounts and fatty acid compositions of 6 commonly consumed fish species were determined. Analyses of fatty acid methyl esters were performed by capillary gas chromatography. Palmitic acid (C16:0) and oleic acid (C18:1ω9) were the predominant saturated and monoenoic fatty acids. The predominant polyunsaturated fatty acids were eicosapentaenoic acid (C20:5ω3) and docosahexaenoic acid (C22:6Ω3). European anchovy and European pilchard are concluded to be good dietary sources of ω3‐polyunsaturated fatty acids, which are known to reduce the risk of cardiovascular diseases because of their high C20:5ω3 and C22:6ω3 content.

The effects of desiccation on seeds of Acer saccharinum and Aesculus pavia: recalcitrance in temperate tree seeds

This study was undertaken to determine how the results from lipid, moisture, and differential scanning calorimetry analyses conducted on silver maple (Aceraceae: Acer saccharinum L.) and red buckeye (Hippocastanaceae: Aesculus pavia L.) compared with those obtained from previous studies on white and water oaks (Fagaceae: Quercus alba and Q. nigra), and the tropical zone species American muskwood (Meliaceae: Guarea guidonia) and carapa (Meliaceae: Carapa guianensis). Seeds were air-dried at room temperature for 9–11 days. At intervals, germination was tested, moisture determined, and lipids extracted. It was found that, like the other recalcitrant seeds, (1) viability was greatly reduced or lost after 11 days of drying, (2) percentage changes in individual fatty acids were not related to seed viability, and (3) results from the differential scanning calorimetry studies revealed a strong relationship between enthalpy/onset data from the embryo and cotyledon tissues and loss of viability. Also, silver maple seeds experienced a 50% reduction in viability by day 5 of drying and retained an axis moisture content over 25% throughout the experiment. However, unlike the other recalcitrant seeds surveyed, both silver maple and red buckeye had a significant reduction in the total amount (mg/g) of cotyledon lipids as the experiment progressed. However, no decrease in the unsaturated/saturated fatty acid ratio was found, so we conclude that in these species lipid peroxidation is not a marker of declining seed viability. Also, red buckeye seeds did not lose 50% viability until after day 8 of the experiment, and axis moisture content fell well below 20% as the seeds dried.

Effect of Partial Gelatinization and Lipid Addition on α‐Amylolysis of Barley Starch Granules

ABSTRACTThe effect of partial gelatinization with and without lipid addition on the granular structure and on α‐amylolysis of large barley starch granules was studied. The extent of hydrolysis was monitored by measuring the amount of soluble carbohydrates and the amount of total and free amylose and lipids in the insoluble residue. Similarly to the α‐amylolysis of native large barley starch granules, lipid‐complexed amylose (LAM) appeared to be more resistant than free amylose and amylopectin. Partial gelatinization changed the hydrolysis pattern of large barley starch granules; the pinholes typical of α‐amylase‐treated large barley starch granules could not be seen. Lipid addition during partial gelatinization decreased the formation of soluble carbohydrates during α‐amylolysis. Also free amylose remained in the granule residues and mostly amylopectin hydrolyzed into soluble carbohydrates. These findings indicate that lysophospholipid (LPL) complexation with amylose occurred either during pretreatment or after hydrolysis, and free amylose was now part of otherwise complexed molecules instead of being separate molecules. Partial gelatinization caused the granules to swell somewhat less during heating 2% starch‐water suspensions up to 90°C, and lipid addition prevented the swelling completely. α‐Amylolysis changed the microstructure of heated suspensions. No typical twisting of the granules was seen, although the extent of swelling appeared to be similar to the reference starch. The granules with added LPL were partly fragmented after hydrolysis.

Evaluating the Cooking and Chemical Characteristics of Low-Fat Ground Beef Patties

Ground beef patties (n=504), manufactured to contain 5, 10 or 15% fat, were evaluated to determine the effects of preparation, storage and cooking methods, and degree of doneness on cholesterol, total lipid, protein, moisture, and energy content. Differences between fresh, hand-made patties and frozen, machine-made patties were statistically significant for some nutrients. However, these differences may be insignificant to consumers because actual differences were small. The greatest difference in composition of the cooked ground beef patties was observed between patties cooked from the frozen state versus fresh patties. Patties cooked from the frozen state were higher in total lipid for each cooking method. An evaluation of cooking methods revealed small differences in total lipid content at the 5% level; however, at the 10 and 15% total lipid levels, microwaved and reheated patties contained the lowest amounts of total lipid while those baked, pan-fried, and broiled contained higher levels. In all total lipid levels and cooking methods except 5% fat broiled/reheated patties, reheating led to a decrease in fat content. Decreases in total lipid content were seen for reheated pan-fried patties at the 5 and 10% levels and reheated patties at the 15% level.

Deficiency in fatty acid synthase leads to premature cell death and dramatic alterations in plant morphology.

An Arabidopsis mosaic death1 (mod1) mutant, which has premature cell death in multiple organs, was isolated. mod1 plants display multiple morphological phenotypes, including chlorotic and curly leaves, distorted siliques, premature senescence of primary inflorescences, reduced fertility, and semidwarfism. The phenotype of the mod1 mutant results from a single nuclear recessive mutation, and the MOD1 gene was isolated by using a map-based cloning approach. The MOD1 gene encodes an enoyl-acyl carrier protein (ACP) reductase, which is a subunit of the fatty acid synthase complex that catalyzes de novo synthesis of fatty acids. An amino acid substitution in the enoyl-ACP reductase of the mod1 mutant causes a marked decrease in its enzymatic activity, impairing fatty acid biosynthesis and decreasing the amount of total lipids in mod1 plants. These results demonstrate that a deficiency in fatty acid biosynthesis has pleiotropic effects on plant growth and development and causes premature cell death.

Relación entre el desayuno y la obesidad en escolares

Breakfast models among children are an issue of public health concern given the association between breakfast and school performance and its potential relationship with obesity. Food intake, energy, and nutrients in the breakfast of 32 school aged children (11-years olds) and its relationship with body mass index (BMI, kg/m2) were examined. The analysis was made by means of anthropometric measurements and a record of weekly food intake using the accurate weighed amount method. The percentage of studied children with overweight/obesity reached 46.9 (weight for height > 90 percentile). The proportional calorie intake in breakfast was lower than that recommended (16.6%). The association observed between caloric percentage of breakfast regarding daily energy and BMI was not significant. Nevertheless, significant correlations were found between fruit group (Pearson r = 0.6286) and protein foods (Pearson r = -0.7653) with BMI. The amount of total lipids (34.4%) and saturated lipids (19.4% in breakfast exceed the recommendations. Further studies are necessary to confirm these data and serve as basis for the design of nutritional education programs.

Growth in excess copper induces changes in the lipid composition and fluidity of PSII‐enriched membranes in wheat

Changes in the lipid composition and fluidity of PSII‐enriched thylakoids were studied in seedlings of wheat (Triticum durum Desf. cv. Adamello) grown in nutrient solution supplemented with CuSO4 to achieve a final concentration of 10 and 50 μM Cu. Metal content increased in the chloroplasts of the 50 μM Cu‐grown plants. PSII isolated from wheat supplied with 10 μM Cu did not show any alteration in the lipid composition or in the lipid and protein levels of the membranes, nor was any change in the ultrastructure of the membranes detected. The 50 μM Cu‐grown plants showed thylakoid swelling, particularly in the stroma and terminal grana thylakoids. Furthermore, an alteration in the lipid composition of PSII preparations was observed together with a decrease in the lipid content, which resulted in a reduction in the lipid to protein ratio. The monogalactosyldiacylglycerol (MGDG) to digalactosyldiacylglycerol (DGDG) molar ratio decreased, whereas the degradation of the polar lipids caused an accumulation of free fatty acids (FFA). The total amount of unsaturated lipids associated with the PSII‐enriched membranes of wheat was not affected by excess copper supplies, even though changes in the individual fatty acids occurred. The effect of copper on the fluidity of PSII membranes was evaluated by electron paramagnetic resonance (EPR) measurements, using spin‐probed fatty acids as probes. The PSII membranes, spin probed by means of 5‐ and 16‐doxylstearic acids, showed that only the fluidity of the surface region of the bilayer close to the polar head group was reduced following the 50 μM Cu supply. In contrast, the fluidity of the inner membrane region of the bilayer did not show any change. The implications of changes in the lipid composition and lipid‐protein interactions on the fluidity of specific transversal membrane regions are discussed.

Growth in excess copper induces changes in the lipid composition and fluidity of PSII-enriched membranes in wheat

Changes in the lipid composition and fluidity of PSII-enriched thylakoids were studied in seedlings of wheat (Triticum durum Desf. cv. Adamello) grown in nutrient solution supplemented with CuSO4 to achieve a final concentration of 10 and 50 μM Cu. Metal content increased in the chloroplasts of the 50 μM Cu-grown plants. PSII isolated from wheat supplied with 10 μM Cu did not show any alteration in the lipid composition or in the lipid and protein levels of the membranes, nor was any change in the ultrastructure of the membranes detected. The 50 μM Cu-grown plants showed thylakoid swelling, particularly in the stroma and terminal grana thylakoids. Furthermore, an alteration in the lipid composition of PSII preparations was observed together with a decrease in the lipid content, which resulted in a reduction in the lipid to protein ratio. The monogalactosyldiacylglycerol (MGDG) to digalactosyldiacylglycerol (DGDG) molar ratio decreased, whereas the degradation of the polar lipids caused an accumulation of free fatty acids (FFA). The total amount of unsaturated lipids associated with the PSII-enriched membranes of wheat was not affected by excess copper supplies, even though changes in the individual fatty acids occurred. The effect of copper on the fluidity of PSII membranes was evaluated by electron paramagnetic resonance (EPR) measurements, using spin-probed fatty acids as probes. The PSII membranes, spin probed by means of 5- and 16-doxylstearic acids, showed that only the fluidity of the surface region of the bilayer close to the polar head group was reduced following the 50 μM Cu supply. In contrast, the fluidity of the inner membrane region of the bilayer did not show any change. The implications of changes in the lipid composition and lipid-protein interactions on the fluidity of specific transversal membrane regions are discussed.

Comparative compositional analysis of walls with two different morphologies: archetypical versus transfer-cell-like

Abnormally thick cell walls of a clonal maize cell line with the labyrinth wall morphology found in transfer cells were analyzed and compared to the relatively thin and even archetypical walls of a sister cell line. Despite a drastic difference in wall morphology between the transfer and archetypical cell walls, the chemical composition of the walls was essentially the same. There were no major differences in the glycosyl residue composition, in the amount of total lipid, and in the amount of total protein. The amounts of wall material released by chemical extraction of cellulosic, hemicellulosic, and pectic fractions were the same for the two types of walls. There were some differences in the protein profile and in the inorganic ion content between the transfer and archetypical walls. These results indicate that profound changes in wall morphology can be brought about in the absence of gross changes in wall composition and suggest that major changes in time- or place-dependent deposition and/or subtle changes in arrangement of rare wall constituents may be responsible.

Organic matter quality and structural stability of a Black Chernozemic soil under different manure and tillage practices

No-tillage (NT) and addition of organic matter can improve soil aggregation and affect soil organic matter (SOM) levels. The effects of short-term (3 years, 1993–1996) conventional tillage (CT), NT, and cattle manure applications on SOM quality and water-stable aggregates (WSA) were investigated on a Melfort silty clay loam (Orthic Black Chernozem) at Melfort (Saskatchewan, Canada). Four methods for managing manure (dry weight basis) within CT and NT were established: fresh manure (FM) was applied at the beginning of the experiment at 23.0 Mg ha −1 and annually at 4.5 Mg ha −1, whereas stockpiled manure (SM) with equal N concentration to FM was applied at the beginning of the study at 23.0 Mg ha −1 and annually at 4.5 Mg ha −1. The control treatment consisted in annual application of 81.0 kg N ha −1 as ammonium nitrate and 9.3 kg P ha −1 as monoammonium phosphate, according to soil test recommendations. Soil samples (0–15 cm) were collected at the end of the 3-year period and lipids were extracted with diethyl ether (DEE) and chloroform (CHCl 3) to assess SOM quality. Water-stable aggregates were measured with and without ethanol pretreatment and before and after extraction of unbound lipids. The amounts of C and N was not affected by the treatments. Between NT and CT, the changes in SOM were expressed by an increase of 21% of the amounts of total extractable lipids (TEL) in the CT soils, whereas in the NT soils, the DEE/CHCl 3 ratio used to assess the degree of biodegradability of OM increased by 40%. Following the application of FM, the stability of soil aggregates against the dissolution and dispersive actions of water decreased by 13 and 16% in CT and NT soils, respectively; however, this effect was compensated by an equivalent increase in resistance to slaking forces. In contrast, the incorporation of SM did not affect the stability of soil aggregates against the dissolution and dispersive actions of water, but increased by 7% the resistance of aggregates to slaking forces.

Relationships between antioxidants, antioxidant enzyme activities and lipid peroxidation products during early development in Dentex dentex eggs and larvae

The overall aim is the characterization of the antioxidant systems in marine fish during early development in order to enhance growth and quality of early life stages by avoiding oxidation problems that may cause pathologies and disease. The present study determined the activities of the antioxidant system enzymes and levels of vitamin E, lipid peroxidation products and fatty acids during early development without exogenous feeding in the marine fish, Dentex dentex. Samples of fertilized eggs just prior to hatch, newly hatched larvae and unfed larvae up to day 9 after hatch were analysed on a daily basis. The larvae did not grow during the experiment and by day 9 the surviving larvae weighed only a third of the newly hatched larvae. Lipid was a major energy source during this period of starvation as evidenced by greatly decreased amounts of total lipid due to a preferential utilisation of neutral lipids. All groups of fatty acids (saturated, monounsaturated and polyunsaturated) were consumed throughout the starvation period. Vitamin E levels were relatively constant until significantly declining by days 8 and 9. Similarly, levels of lipid-soluble fluorescent products (LSFP) were relatively constant until day 6 and then significantly decreased from days 7 to 9. In contrast, the level of malondialdehyde (MDA) was very high in eggs but was 3-fold lower in newly hatched larvae and then decreased over the whole time-course and was also significantly lower on days 8 and 9. The activities of enzymes of the antioxidation system were expressed in both eggs and early larvae and varied during the developmental period with levels of catalase and glutathione peroxidase (GPX) being initially low in eggs whereas glutathione- S-transferase (GST) and superoxide dismutase (SOD) were higher in eggs than in larvae. Overall, the activities of catalase and GPX increased, whereas GST and total SOD activities decreased, during the early stages of development during a period where there was no exogenous dietary input into the larvae. Glutathione reductase activity was very low and showed an increasing trend initially until days 2–3 before declining and varying over the remaining period. In conclusion, we determined the prooxidant (polyunsaturated fatty acid) status, antioxidant status (vitamin E), peroxidation status (MDA and LSFP) and the activities of the antioxidant enzyme systems in a single integrated study in unfed marine fish larvae during early development.

Kinetic and Thermodynamic Aspects of Lipid Translocation in Biological Membranes

A theoretical analysis of the lipid translocation in cellular bilayer membranes is presented. We focus on an integrative model of active and passive transport processes determining the asymmetrical distribution of the major lipid components between the monolayers. The active translocation of the aminophospholipids phosphatidylserine and phosphatidylethanolamine is mathematically described by kinetic equations resulting from a realistic ATP-dependent transport mechanism. Concerning the passive transport of the aminophospholipids as well as of phosphatidylcholine, sphingomyelin, and cholesterol, two different approaches are used. The first treatment makes use of thermodynamic flux-force relationships. Relevant forces are transversal concentration differences of the lipids as well as differences in the mechanical states of the monolayers due to lateral compressions. Both forces, originating primarily from the operation of an aminophospholipid translocase, are expressed as functions of the lipid compositions of the two monolayers. In the case of mechanical forces, lipid-specific parameters such as different molecular surface areas and compression force constants are taken into account. Using invariance principles, it is shown how the phenomenological coefficients depend on the total lipid amounts. In a second approach, passive transport is analyzed in terms of kinetic mechanisms of carrier-mediated translocation, where mechanical effects are incorporated into the translocation rate constants. The thermodynamic as well as the kinetic approach are applied to simulate the time-dependent redistribution of the lipid components in human red blood cells. In the thermodynamic model the steady-state asymmetrical lipid distribution of erythrocyte membranes is simulated well under certain parameter restrictions: 1) the time scales of uncoupled passive transbilayer movement must be different among the lipid species; 2) positive cross-couplings of the passive lipid fluxes are needed, which, however, may be chosen lipid-unspecifically. A comparison of the thermodynamic and the kinetic approaches reveals that antiport mechanisms for passive lipid movements may be excluded. Simulations with kinetic symport mechanisms are in qualitative agreement with experimental data but show discrepancies in the asymmetrical distribution for sphingomyelin.

Biochemical aspects of flight and flightlessness in Gryllus: flight fuels, enzyme activities and electrophoretic profiles of flight muscles from flight-capable and flightless morphs

Female Gryllus assimilis subjected to 4.5–7.7 h continuous tethered flight had significantly lower amounts of total lipid, triglyceride and total soluble carbohydrate compared with unflown controls. A much greater amount of total lipid (6.3 mg) was used during flight compared with carbohydrate (0.14 mg). Flown individuals also had substantially reduced amounts of injected, radiolabeled [ 14C]-oleic acid. Activities of lipid, carbohydrate and amino acid catabolizing enzymes in flight muscles of G. assimilis and its wing-polymorphic congener, G. firmus, were very similar to activities in insects which primarily utilize lipid to power flight. By contrast, enzyme activities were very different from those in insects which primarily or exclusively use carbohydrate or proline as a flight fuel. These results strongly implicate lipid as the major flight fuel in Gryllus. Previous studies have shown that lipid levels are higher in flight-capable (long-winged) G. firmus that have small ovaries compared with flightless (short-winged) females that have large ovaries. Results of the present and previous studies collectively indicate that elevated lipid in long-winged G. firmus represents an energetic cost of flight capability which reduces (trade-offs with) reproduction in Gryllus. In G. firmus, mass-specific activities of nearly all enzymes were considerably reduced in underdeveloped, and to a lesser degree in histolyzed muscle, compared with fully-developed flight muscle. An important exception was alanine aminotransferase, whose activity was the highest in histolyzed muscle, and which may be involved in the catabolism of amino acids derived from muscle degradation. Despite the dramatic differences in enzyme activity, electrophoretic profiles of soluble flight-muscle proteins differed only subtly between fully-developed and underdeveloped or histolyzed flight muscles.

Nutritional Effects of Dietary Diacylglycerol as a Cooking Oil

Diacylglycerols (DG) are naturally structural lipids, existing as the form of 70% 1, 3-DG and 30% 1, 2-DG in nature respectively, which suppressed the reconstruction of triacylglycerols (TG) in blood compared with the ingestion of a similar fatty acid composition of dietary TG. This effect is owing to that the 1-monoacylglycerole of a digest from 1, 3-DG by lipase has less substrate specificity against reconstitution enzyme of TG and subsequently is digested to glycerol and fatty acid in intestine epithelial cell, and then the fatty acid which pours into liver via portal vein is finallyd ecomposed by b-oxidation. The interesting nutritional aspect of DG is the residual serum TG after lipid ingestion could be decreased by ingestion of DG in the subjects especially with a higher serum TG concentration in fasting. When lipoproteins were fractionated from blood after DG ingestion, the chylomicron production significantly decreased less than 50% of that by TG ingestion due to the suppression of reconstructing TG and utilizing cholesterol in intestine epithelial cell. Long-term for 12 weeks, the effects of DG ingestion on lipid metabolism of human was examined at the dose of lOg when total amount of dietary lipids was strictly restricted at 50g a day. The fat in liver and the visceral fat significantly decreased in the DG diet group compared to that of TG diet group. Thus, DG would appear to be an ideal source of energy, assuring less fat accumulation by decreasing in serum insulin and fatty acids compared to TG.

Utilization of human blood and sugar as nutrients by female Aedes aegypti (Diptera: Culicidae).

We examined the utilization of sugar and human blood as nutrient sources for small and large female Aedes aegypti (L.) when they were fed blood 2 or 5 d after emergence. Laboratory-reared mosquitoes were fed human blood alone or sugar plus human blood and assayed at 4, 12, 24, and 48 h after the blood meal. Starved and well-fed mosquitoes were obtained by holding teneral females (< or = 1 d old) with 0, 5, 10, and 15% sucrose solutions ad libidum from emergence. Both small and large mosquitoes increased their glycogen and sugar levels significantly by feeding on blood only or on blood plus sugar when they imbibed a human blood meal on day 2 after emergence. Mosquitoes only fed blood on day 2 had the highest lipid levels of any treatment group. Both size classes and all feeding regimes failed to increase the total amount of glycogen, lipid, or sugar when they fed on blood 5 d after emergence. We conclude that there is an energetic advantage to Ae. aegypti when they feed on blood early in adult life (< or = day 2 after emergence).

Growth and Oil Production of Apiotrichum curvatum in Tomato Juice

The lipid-accumulating yeast Apiotrichum curvatum ATCC 20509 (formerly Candida curvata D) grew in shake flask culture in freshly prepared tomato juice or tomato pulp; growth was improved when the medium was supplemented with sucrose and a basal salts mixture. Under controlled conditions in the fermentor, biomass and oil production reached a maximum at 96 h, compared with 130 h in shake flasks. Biomass production increased with the addition of 0.3% (wt/vol) urea to the juice, but decreased with the addition of 0.5% (wt/vol) yeast extract or Casamino Acids. The total amount of lipid produced and the percent of intracellular oil per cell dry weight were greatest in juice supplemented with 0.3% urea.

Differences between Bligh and Dyer and Soxhlet extractions of PCBs and lipids from fat and lean fish muscle: Implications for data evaluation

Both Bligh and Dyer extraction using chloroform/ methanol and Soxhlet extraction using hexane/acetone were employed for extracting total lipid and polychlorinated biphenyls (PCBs) from muscle tissue in four species of fish: herring ( Clupea harengus), salmon ( Salmo salar), cod ( Gadus morhua) and Northern pike ( Esox lucius), all caught in the southern part of the Baltic Sea. The Bligh and Dyer method allowed a greater amount of total lipid but a lesser amount of total PCBs to be extracted than the Soxhlet method with hexane/acetone did. For all the fish except cod, the sample wet weight PCB concentrations differed significantly for the two extraction methods. When the sample PCB was normalized to extracted total lipid, the differences in the yield of the two methods increased due to differences in total lipid yield. This was most pronounced for the lean fish (cod and pike). When the two methods were compared in terms of efficiency in the extraction of different PCBs, a relationship of this to PCB congener lipophilicity, expressed in terms of K ow, could be shown. Differences between methods and variability within the data provided from the first method were highest for the PCB congeners in the lipophilicity regions of log K ow < 6.5 and > 7.5. The study indicated that comparability is better for PCB analysis data from triacylglycerol-rich samples (herring and salmon) than from lean samples (cod and pike). The results suggest that in order to avoid comparisons of data from different samples being misleading, PCB pattern and/or single congener data should be obtained using the same extraction technique.